Merge pull request 'The assigner puts only changed values and keeps a placed node's record ask while it waits (issue 774)' (#121) from fix/assigner-puts-only-changes into main

modules/mesh-delivery-assigner/cmd/mesh-delivery-assigner/pass.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"bytes"
 	"context"
 	"encoding/json"
 	"errors"
@@ -566,6 +567,11 @@ func (p *passer) put(ctx context.Context, bucket, key string, encode func() ([]b
 		p.logf("%s %s is not written: %v", bucket, key, err)
 		return
 	}
+	// A value the bucket already holds is not put again: every put is a change its watchers hear, and a want put unchanged
+	// made its node compose again (issue 774, 2026-10-31: novox composed every 8 s, two asks of the vault each time).
+	if held := p.w.value(bucket, key); held != nil && bytes.Equal(held, value) {
+		return
+	}
 	if _, err := p.kvs[bucket].Put(ctx, key, value); err != nil && !errors.Is(err, context.Canceled) {
 		p.logf("%s %s could not be written: %v", bucket, key, err)
 		return
@@ -645,6 +651,14 @@ func (p *passer) staleAsk(key string, trunk map[string]delivery.Module) bool {
 		if !on {
 			return true
 		}
+		// A node that composes its own asks about its own composition, which its have names as the one it waits on (yeses): that
+		// ask stands while the have waits on it, whatever the controller composes (issue 774, 2026-10-31: novox's asks of
+		// postgres, keycloak and mongodb were taken away and made again under a new id every pass, so no answer could count).
+		if hkey, err := delivery.HaveKey(k.Node, k.Module); err == nil {
+			if h, err := delivery.DecodeHave(p.w.value(delivery.HaveBucket, hkey)); err == nil && h.Phase == delivery.PhaseWaitingYes && h.Waits == k.Composed {
+				return false
+			}
+		}
 		// The assigner asks about a composition at more than the trunk fingerprint: a node held back by the rules is asked about the
 		// revised composition of the fingerprint it runs (ADR 0545), and a node's first want at the older fingerprint it runs. So a
 		// record ask is stale only when its digest is the composition of none of the fingerprints the node can still want (the

modules/mesh-delivery-assigner/cmd/mesh-delivery-assigner/pass_test.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"bytes"
 	"context"
 	"encoding/json"
 	"errors"
@@ -26,10 +27,12 @@ import (
 type memKV struct {
 	jetstream.KeyValue
 	values map[string][]byte
+	puts   int // how many puts reached the bucket
 }
 
 func (m *memKV) Put(_ context.Context, key string, value []byte) (uint64, error) {
 	m.values[key] = value
+	m.puts++
 	return uint64(len(m.values)), nil
 }
 
@@ -952,6 +955,30 @@ func aPlacedNodesWantsNameTheBuildAloneAndItsYesComesFromItsHave(t *testing.T) {
 	if _, there := asksKV.values[akey]; !there {
 		t.Fatal("a have waiting for a yes raised no record ask")
 	}
+	// Issue 774, 2026-10-31: while the controller still composes the placed node's module (its lease not handed away), its
+	// digests are not the one the node's have waits on; the ask stays, and a pass that changes nothing puts nothing: on novox
+	// the asks of postgres, keycloak and mongodb were taken away and made again every 8 s, and a want put unchanged each
+	// pass made the node compose again each time.
+	for _, fp := range []string{fpTest, fpOld} {
+		ck, _ := delivery.ComposedKey("g14", "web", fp)
+		cv, _ := delivery.EncodeComposedDigest(delivery.ComposedDigest{Digest: "sha256:" + strings.Repeat("c", 64), Judgement: delivery.JudgedUnchanged})
+		put(delivery.ControllerComposedBucket, ck, cv)
+	}
+	asked := asksKV.values[akey]
+	p.wants(context.Background())
+	if !bytes.Equal(asksKV.values[akey], asked) {
+		t.Fatalf("the record ask the node's have waits on was taken away or made again: %q", asksKV.values[akey])
+	}
+	wantPuts, askPuts := wantsKV.puts, asksKV.puts
+	p.wants(context.Background())
+	if wantsKV.puts != wantPuts || asksKV.puts != askPuts {
+		t.Fatalf("a pass that changed nothing put %d wants and %d asks", wantsKV.puts-wantPuts, asksKV.puts-askPuts)
+	}
+	// Whichever rule asks it, a want put with the value the bucket holds reaches no bucket: each put is a change its node hears.
+	p.put(context.Background(), delivery.AssignerWantsBucket, wkey, func() ([]byte, error) { return wantsKV.values[wkey], nil })
+	if wantsKV.puts != wantPuts {
+		t.Fatalf("a want put unchanged reached the bucket")
+	}
 	a, err := delivery.DecodeAssignerAsk(akey, asksKV.values[akey])
 	if err != nil {
 		t.Fatal(err)